The mainstream production processes of Ammonium Metatungstate mainly include the following:
Extraction and synthesis from tungsten ore
Tungsten ore extraction: use strong acid such as hydrofluoric acid or sulfuric acid to extract tungsten elements from tungsten ore, forming tungsten slurry suspension, and then filtering to remove sand particles to get a certain concentration of solution.
Tungsten nitrate precipitation
The solution obtained in the previous step is added with excess nitric acid, so that the tungsten element in the solution undergoes redox reaction to form tungsten oxide, and then the fine particles in the solution are precipitated out, i.e. tungsten nitrate.
Addition of ammonia
Put tungsten nitrate into ammonia water, and add ammonia under appropriate temperature condition, so that tungsten nitrate undergoes hydrolysis reaction to form ammonia and metatungstic acid, and after precipitation, ammonium metatungstate can be obtained. There are mainly the following methods for preparing ammonium tungstate flake with ammonium tungstate solution as raw material.
Solvent extraction or ion exchange method
Ammonium metatungstate solution is firstly prepared, and then ammonium metatungstate is obtained by evaporation and crystallization.
Preparation with sodium tungstate solution as raw material:
Solvent extraction method
AMT solution is prepared, and then ammonium metatungstate is obtained by evaporation and crystallization.
Heat to thermally dissociate the APT (which probably means some kind of tungstate precursor):
So that it loses part of the ammonium and water of crystallization, converted into ammonium metatungstate which is soluble in water, and then obtained ammonium metatungstate by evaporation and crystallization.
Neutralization method
Prepare ammonium metatungstate with ammonium sec-metatungstate and nitric acid as raw materials, and get ammonium metatungstate by controlling the conditions of solid-liquid ratio, pH value, heating temperature and time.
Tungstic acid method
Dissolve tungstic acid with ammonia, add it into boiling deionized water, heat and expel ammonia under stirring, adjust pH value, heat and concentrate, cool and filter, add ethanol and stir, filter after settling, and then dry the crystals at specific temperature and crush them to get the product.
Thermal decomposition method
Take ammonium paratungstate as raw material, carry out thermal decomposition under specific temperature, remove part of ammonia and water, get ammonium metatungstate.
Methods of preparing ultrafine particles of ammonium metatungstate
Including solvent crystallization method, hydrothermal synthesis method, gas phase condensation method and milling method, etc. These methods can get ultrafine particle ammonium metatungstate by controlling different parameters, such as solvent volatilization rate, reaction temperature, reaction time, etc.. The selection of these production processes depends on factors such as the availability of raw materials, equipment conditions, the characteristics of the target product (e.g., particle size, purity, etc.), and cost.
More details of ammonium metatungstate product, please visit website: http://ammonium-metatungstate.com/
Please contact CHINATUNGSTEN for inquiry and order of ammonium metatungstate:
Email: sales@chinatungsten.com
Tel.: 86 592 5129595
